Nutrient compositions with preservative properties are of great need for a variety of agricultural applications, such as, for example, hydroponics where oxygen deficient media results in favorable conditions for undesirable microbial growth, as well as for pre-harvest and post-harvest crop maintenance. However, it is critical that the preservative constituents of the composition do not interfere with plant growth, development, and/or quality. Free oxygen radicals, for example, which may have biocidal activity, can underlie basic plant signaling and stress responses [Demidchik et al., Free oxygen radicals regulate plasma membrane Ca2+- and K+-permeable channels in plant root cells, J. Cell Science 116(1):81-88 (2003)], and their reaction products can inhibit plant growth [Date et al., Effects of chloramines concentration in nutrient solution and exposure time on plant growth in hydroponically cultured lettuce, Scientia Horticulterae 103(3):257-265 (2005)].